White steam / smoke

75, if it leaks under pressure...it'll leak under vaccuum(sp?)

Boat doc,

I started another thread about an overheating problem I am having, but have been watching this thread too. I have overheated twice in the past month, first time temp gauge went up, second time it didnt. Ran boat several hours between the two incidents and it was fine. I noted what you said about leaking RWP. I replaced my impellor this spring(Chev 305 w/OMC conv - big impellor-big fins)
I had to fashion my own new gasket. It drips ever so slightly with garden hose hook up. Drip goes away when engine is running. Since the overheating just started this year (after the pump servicing) could that ever so slight a leak be indicative of enough air getting in to cause a problem. Note: I ran over 20 hours this year before the problem showed up. If you have a moment, look at my "overheating" thread that has some more detail. I'd appreciate your input.

Thanks,

Larry

Boat doc

I think I disagree with you on this one some days I get steam along with my water coming out of the exhaust. I know I have no cooling issues as I can hang on to the manifolds at idle and WOT all day long.

Now I agree with you that if he can not hold onto his manifolds and risers he has a problem. But once he can hold on to them and he gets a some steam from the exhaust outlets then he is ok.

Another thought, and I know the weather conditions have been discussed, but the water temp where I am running is nearly 90. At that temp, can I still expect the engine temp to stay right near 160? I even put a 140 tstat in, but the temp still hovers just north of 160 when at idle and lower RPM's and goes up to about 190-200 after a high speed run and then drops back down.

Azeus17,

I don't think I ever solved anything on mine. I still have a steam issue. I don't think mine is just weather or climate related, as it does it when it is hot or cold, wet or dry outside. We pulled the boat to Lake Lanier in GA this summer and it even did it there.

While the steam is there most of the time at acceleration, I don't seem to have any other problems. Boat runs pretty good and temp gauge stays from 150 - 165. We are just using it as is.

Over the winter, I may swap out the raw water pump and hoses from the intake to the pump.

Have you run the raw water pump test? That can show you a lot.

Went out today and checked temp of risers. I can't leave my hand on them for 5 seconds. Did some of the above prescribed work today.
1. checked water pump flow. ok
2. chased all hoses from water pump through thermostat to manifolds. ok

I've never burned up an impeller since I've owned the boat. Now I'm wondering if the PO did and there are pieces in the manifold or something. What do you suggest next? I guess checking to see if the riser gasket is turned the wrong way, but I'm nearly certain it's turned so the blocked portion is toward the stern...I remember following skidim instructions when I changed them.

This is starting to bug me and I didn't even know it's a problem. I did notice that there was steam coming through many, many boats' exhaust tonight though. Does humidity matter? We have steam coming off our grass most summer mornings here...
Either way, according to you guys, my risers are way too hot.

Put the new riser gaskets on with the exhaust outlet side (back) blocked. It was better. Still got some steam / smoke at full throttle, but not much. Did not have any when accelerating. Definitely better.

Came back down the canal (couple minutes at idle). Risers were not as hot as before, but still hot. Could hold hand on there for a few seconds, maybe 10, but not indefinitely.

My raw water pump test results from a few days ago were:
With boat in the water, hose from top of raw water pump filled a 5 gallon bucket at 2500 rpm in 21 seconds.
Hose going into driver's side manifold filled just under half of the 5 gallong bucket in 20 seconds.

Manifolds and risers are new.

Any thoughts.

79,

That is what I thought also. When Marks said that, I checked Skidim's website. It says:

"GSKT EXHAUST RISER
PCM FORD AND PCM GM SMALL BLOCKS
The blocked water passage goes towards the exhaust outlet. Same Gasket 3" and 3.5" Risers."

I'll call Vince in the morning to make sure. Had to order 2 new ones from them tonight anyway. Took the risers off tonight, but no way to save the gasgets.

the riser gasket blocks off the front passage not the rear passage or the two side passages. If it is blocking the rear passage then all of the water almost instantly goes out the riser and does not circulate in the manifolds. Call Vince and double check me but I'm almost 99% sure that's the way it should be.

Bwill, just got back from Rocky Point in Mexico. From your post above I must agree with the post from the more senior members concerning your riser temps. If 2-3 secs is as long as you can hold your hand on the riser, that does sound too hot. Especially since you just idled through your canal for a couple mins. From your water flow tests, it sounds as though everything is okay with your pump. Double check the gaskets and reply back.

Marks,

I think you are right. Somehow, I had in my mind that the blocked port is in the front. I will fix it tonight and see if that solves.

GottaSki,

I have never set timing before, but would love to know how to do it. I have wanted to post my restart issue, but can already see 79's post about not messing with the carb adjustments until timing is set. How hard is setting the timing?

Thanks,

Brent

Brent,

I think you may have the gaskets in backwards. According to skidim's description, the blocked port goes towards the exhaust outlet.

Tim,

The manifolds and risers were new with the rebuild. Have not had any impeller issues since then. Plus, it would be both of them. I checked the gasket between riser and manifold visually. The tab that sticks out is on the back side. Looked on Skidim and that would put the blocked part of the gasket on the front side above the water in line.

Any thoughts?

Mark,

I do it get it consistently, when really taking off or near full throttle. It is low 90s everyday here now and pretty humid. Although I noticed the steam/smoke on one other Mastercraft this weekend, I don't see it on others.

Nutty,

I live on a canal. We went out wakeboarding for a while today. Came back down the canal at idle for a couple minutes. Opened the cover with the boat still at idle. Could only keep my hand on the top of the riser for 2-3 seconds. It felt pretty hot. Engine temp gauge said 150.

Just trying to think of anything else that could matter:
-I installed the electronic ignition from skidim over the winter, but did not put a new cap or wires on.
-Even when warm, if I turn the boat off (to swap skiers, etc) and then restart, I have to usually give it a little throttle. Without it, it will kick, but more time then not, will not start. A little throttle and it fires right up.
These probably don't matter with my steam/smoke issue, but just thought I would mention in case.

Thanks,
Brent

If your gaskets are installed correctly between the manifolds and the risers like Doc suggested in an earlier post I believe you are okay based on the information you gave me above. After you get your boat in the water and run it (at moderate speeds) for a little while, leave the engine running at idle for a minute or two and then put your hand on the riser. See how long it takes before you have to pull your hand away. Time this and tell me how long. Of course this is no scientific test, but I'm just curious. I'm going to do the same with mine. Get back to this thread with your results and happy boating! Brian